#include <stdio.h>
#include <string.h>

int main(int argc, const char *argv[])
{
	char buff[128] = {0};
	gets(buff);

	int i = strlen(buff) - 1;
	int j = 0;

	while(j < i){
		if(buff[j] != buff[i]){
			break;	
		}
		j++;
		i--;
	}
	if(j < i){
		printf("不是回文字符串\n");
	}else{
		printf("是回文字符串\n");
	}

	return 0;
}
